Polyaxial pedicle screw assemblies are well known in the art and may be used for connecting vertebrae or other spinal structure to rods in spinal surgery. For example, polyaxial pedicle screw assemblies are known that incorporate a ball joint at the connection to the rod to allow the surgeon some flexibility in placing the screws. Tightening a nut on the screw compresses the ball joint components to lock the angular position of the ball joint.